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The
National List of Plant Species
That Occur in Wetlands
The National List of Plant Species That Occur in Wetlands (hereafter referred to as the National List) represents the combined efforts of many biologists over the last decade to define the wetland flora of the United States. The National List has undergone a number of revisions based on intensive review by regional ecologists. National, Regional, and State lists are being distributed to provide users with the most current information. We welcome and encourage modification and improvement of the National List. Refinement of the National List will occur continually, reflecting increased knowledge in Indicator assignments, taxonomy, and geographic distribution. We anticipate that further refinement of the National List will lead to additional infra-specific and subregional Indicator assignments.
The U.S. Fish and Wildlife service initially developed the National List in order to provide an appendix to the Classification of Wetlands and Deep water Habitats of the United States (Cowardin et al. 1979) to assist in the field identification of wetlands. Plant species that occur in wetlands as used on the National List are defined as species that have demonstrated an ability (presumably because of morphological and/or physiological adaptations and/or reproductive strategies) to achieve maturity and reproduce in an environment where all or portions of the soil within the root zone become, periodically or continuously, saturated or inundated during the growing season (adapted from Huffman 1981).
The development of the National List changed significantly when a cooperative review effort was established by the major Federal agencies involved in wetland identification and management. The utility of the National List goes far beyond a simple catalog of wetland plants. The Fish and Wildlife Service, in cooperation with North Carolina State University, has produced a weighted average procedure for using the wetland Indicator assignments of individual species to assist in determining the probability that a community is a wetland (Wentworth and Johnson 1986). This procedure is used by the Soil Conservation Service to aid in the determination of wetlands included under the conservation provisions of the Food Security Act of 1985.
The Fish and Wildlife Service, Army Corps of Engineers, Environmental Protection Agency, and Soil Conservation Service use the National List to aid in identifying wetlands falling under their various wetland program responsibilities. Wetland identification manuals which incorporate the National List have been produced by the Corps of Engineers (Environmental Laboratory 1987) and the U.S. Environmental Protection Agency (Sipple 1988).